<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <title>颜色_第1种表示_颜色名</title>
    <style>
        .atguigu {
            color: blue;
        }
    </style>
</head>

<body>
    <h2 class="atguigu">尚硅谷</h2>
</body>

</html>